Abstract
Triterpenoids of ferns are biosynthesized from squalene in contrast to those of higher plants, except cycloartanoids. Therefore, most of them have no oxygen function at C-3. Characteristic triterpenoids of ferns are diploptene and fernene. Adiantum ferns of Parkeriaceae contain norhopanoid such as adiantone, in contrast to related Cheilanthes that elaborates sesterterpenoids along with triterpenoids. Polypodiaceous ferns are morphologically simple and hard to be classified. However their triterpenoids are peculiar to the genus and/or species. Bi~tetracyclic triterpenoids and pentacyclic triterpenoids were isolated from Polypodiaceous ferns and many peculiarities have been observed in their triterpenoid constituents. Polypodiodes ferns contain β-amyrin acetate along with related hydrocarbons. Colysanoxide along with α-onoceradiene has been isolated only from Colysis group. Pyrrosia group contains hopane and dammarane triterpenoids along with cyclohopanediol with a novel skeleton. Lemmaphyllum group is the most interesting group of ferns because of skeletal diversity of triterpenoids. Interesting chemotaxonomic examples will be discussed.
